Fatma Saeed Alqahtani1, Karim Hamda Farhat2, Mashael Marzouq Alshebly31 Department of Pathology, College of Medicine, King Saud University and King Saud University Medical City, Riyadh, Saudi Arabia2 Cancer Research Chair, College of Medicine, King Saud University, Riyadh, Saudi Arabia3 Department of Obstetrics and Gynecology, College of Medicine, King Saud University and King Saud University Medical City, Riyadh, Saudi Arabia

Objective: This study was aimed to compare the results of immunophenotyping by flow cytometry (FC) and immunohistochemistry (IHC) in the diagnosis of B-cell lymphomas and classic Hodgkin's lymphoma (cHL). Methods: This was a retrospective cohort study of 280 patients with chronic B-cell neoplasms and cHL performed between 2008 and 2013. Percentages of B- and T-cell markers detected by FC and IHC were compared regardless of the final diagnosis. Results: FC and IHC results were obtained from 280 patient medical records. There were 155 (55.4%) patients with non-Hodgkin's lymphoma (NHL), 110 (39.3%) with cHL, and 15 (5.4%) with chronic lymphocytic leukemia (CLL). Disparity between FC and IHC was observed for CD19 expression in cHL group where 73.6% (n = 81) CD19 expression was detected by FC and 59.1% (n = 65) detected by IHC (P < 0.02). In NHL group, a higher percentage (81.3%; n = 126) of CD19 was detected by FC as opposed to 61.3% (n = 95) detected by IHC (P < 0.0001). CD19 expression was no different between the two groups. CD20 expression assessed by FC (61.3%; n = 95) was lower than 85.2% (n = 132) detected by IHC in NHL group (P < 0.0001). Whereas no differences were observed in cHL, IHC performed better (100%; n = 15) than FC (66.7%; n = 10) for CD20 detection in CLL group (P < 0.01). In cHL and NHL groups, flow cytometric detections of CD21 of 61.8% and 56.1% were higher than 46.4% (P < 0.02) and 41.9% (P < 0.01) detection rates by IHC. No disparities were observed between FC and IHC detection rates for CD5, CD10, CD23, and CD30 expressions. Conclusion: There was a considerable amount of disparity between FC and IHC results, warranting further evaluation.